David, Just to clarify, there are steel springs in the (rear) suspension. The hydropneumatic compensator does just that, it compensates for load on the rear suspension and is intended to maintain a specific ride height. Often mistakenly considered nothing more than a big shock absorber, it’s actually a fairly complex device with internal valving to control its operation.
[genuine-mercedes-benz-hydropneumatic-compensator-shock-w108-w110-w111__20719.1625604934.386.513.jpg] ZF made these, and I found a link I had to their former web page with a description of the “Nivomat” as it was branded by them: <https://web.archive.org/web/20161228044629/http://www.zf.com/corporate/en_de/products/product_range/cars/cars_nivomat.shtml> Cars | Nivomat® - ZF Friedrichshafen AG<https://web.archive.org/web/20161228044629/http://www.zf.com/corporate/en_de/products/product_range/cars/cars_nivomat.shtml> web.archive.org<https://web.archive.org/web/20161228044629/http://www.zf.com/corporate/en_de/products/product_range/cars/cars_nivomat.shtml> [X]<https://web.archive.org/web/20161228044629/http://www.zf.com/corporate/en_de/products/product_range/cars/cars_nivomat.shtml> Due to the cost of the device, when they failed a lot of owners opted to go with a fixed steel spring instead of the compensator, as it was easy to retrofit. Also, not all of the models with swing axles had a compensator, some came from the factory with the spring setup, as in a lot if not all of the W110 and W111 models that used the same rear axle setup. Jamie is probably far better versed on these than me, so I’ll certainly defer to him or anyone else that is more knowledgable. Enjoy! -D On Jul 13, 2024, at 1:33 PM, David Bruckmann via Mercedes <mercedes@okiebenz.com> wrote: I can't speak to values, other than to echo Dan that generally the crappy ones aren't worth the effort. And sedans anyway are not worth as much as a coupé or convertible. As to the hydropneumatic compensator: a clever but poorly understood contraption mounted in place of the transverse steel spring on the rear differential. The idea is that, with some movement over uneven pavement, the compensator would pump itself up against a nitrogen cushion to provide height control. Same principle as the hydropneumatic system on the station wagons: the system only provided a "levelling" function. The clever part being that the hydropneumatic compensator did not require a pump because it did that part itself! They were made by Boge and are available rebuilt provided you have a core to supply. Last time I checked it was ~$1,500 for a rebuild. I'm sure they replace a bunch of seals and stuff, but most probably all that fails is they lose the nitrogen gas charge. Same thing happens on the station wagons and for that matter the 6.9 system. Different again (essentially a copy of Citroën's system in the DS from 1955) because there are literally NO steel springs. The car is totally dependent on the hydraulic system to stay "up", hence the way the 6.9s sink to the ground if not used. NOT like the W100 and W109 systems, which use air, not hydraulic pressure. I swapped in the (easily available from Mercedes) spring on my W108 in place of the compensator. Took about 15 minutes. I have kept it just in case... D. On Sat, 13 Jul 2024, Kaleb Striplin wrote: What would a reasonable amount to pay for one in decent cosmetic shape that might need some reasonable mechanical work? I would prefer a 4.5, I think. I have never had a 108 aside from a few parts cars. I know there is some sort of issue with hydraulic suspension compensator something or other. _______________________________________ http://www.okiebenz.com To search list archives http://www.okiebenz.com/archive/ To Unsubscribe or change delivery options go to: http://okiebenz.com/mailman/listinfo/mercedes_okiebenz.com
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